At that time, had you recently traveled to any other countries? Made multi-city trips instead of round trips? Changed an international flight at the last minute, or missed a flight and ended up at a different destination?

I've heard from people who had to change flights/destinations at the last minute that they had a lot of trouble with security at the airport when they arrived. Just an idea.

Eh, I had traveled to Canada to look at some universities right before college and went to Nassau in the Bahamas for spring break my Sophomore year of college but that was about it. I don't think either of those locations would have put me on any list. Although I was pretty notorious for "missing" my flight and flying standby a little later that day or the next day so I could have more time where ever I was.